1. Field of the Invention
The present invention relates to matte finish, i.e., non-shiny polyethylene films, for example, embossed films having improved tape adhesion. More particularly, the invention concerns linear low density polyethylene containing a specific comonomer for use in low gloss surface applications.
2. Related Art
Many applications of polyethylene films require a low gloss surface. That is the surface may be embossed or patterned for aesthetic or useful reasons. For example, one utilization where a reduced gloss finish is required is on the back sheet of a disposable diaper. Disposable diapers are conventionally constructed of an absorbent inner layer disposed between a non-woven permeable top sheet and a film back sheet having closure tabs to secure the diaper in place.
The back sheet (outer sheet) may be embossed in order to reduce the gloss to an acceptable level. Embossing or other methods of reducing surface gloss also materially reduce the adhesion of the reduced gloss surface for the closure tabs thereby causing the diaper to be insecure in use, that is, the tabs may peel and release the diaper from an infant.
There are various methods which may recover or improve the lost adhesion of the tabs to the back sheet, such as longer adhesive tabs, tackier adhesives, corona discharge treatment of the back sheet film and careful control of the profile of the embossed surface, the latter being disclosed in U.S. Pat. No. 4,436,520.
The present invention provides the advantage that ordinary embossing or surface matting procedures may be employed with improved tab adhesion. It is also an advantage that the present invention does not cause a problem with handling of the back sheet stock manufacture. For example, light corona treatment to enhance the peel force could result in film roll blocking during unwinding. It is a particular feature that the improved tab adhesion of the present invention does not require a separate process step such as corona discharge. Hence it is a feature of the present invention that a very specific type of polyolefin film material is used for the low gloss films to have improved adhesion properties on low gloss surfaces. These and other advantages and features will become apparent from the following disclosure.